Experimental allergic encephalomyelitis (EAE) is an autoimmune disease of the central nervous system mediated by CD4+ T cells reactive with myelin basic protein (MBP). Rats were rendered resistant to the induction of EAE by vaccination with synthetic peptides corresponding to idiotypic determinants of the beta chain VDJ region and J alpha regions of the T cell receptor (TCR) that are conserved among encephalitogenic T cells. These findings demonstrate the utility of TCR peptide vaccination for modulating the activity of autoreactive T cells and represent a general therapeutic approach for T cell-mediated pathogenesis.

Rheumatoid arthritis (RA) is a disease affecting the synovial membranes of articulating joints that is thought to result from T-cell-mediated autoimmune phenomena. T cells responsible for the pathogenesis of RA are likely present in that fraction of synovial T cells that expresses the interleukin 2 receptor (IL-2R), one marker of T-cell activation. We report herein an analysis of T-cell receptor (TCR) beta-chain gene expression by IL-2R-positive synovial T cells. These T cells were isolated from uncultured synovial tissue specimens by using IL-2R-specific monoclonal antibodies and magnetic beads, and TCR beta-chain transcription was analyzed by PCR-catalyzed amplification using a panel of primers specific for the human TCR beta-chain variable region (V beta). Multiple V beta gene families were found to be transcribed in these patients samples; however, three gene families, V beta 3, V beta 14, and V beta 17, were found in a majority of the five synovial samples analyzed, suggesting that T cells bearing these V beta s had been selectively retained in the synovial microenvironment. In many instances, the V beta 3, V beta 14, or V beta 17 repertoires amplified from an individual patient were dominated by a single rearrangement, indicative of clonal expansion in the synovium and supportive of a role for these T cells in RA. Of note is a high sequence similarity between V beta 3, V beta 14, and V beta 17 polypeptides, particularly in the fourth complementarity-determining region (CDR). Given that binding sites for superantigens have been mapped to the CDR4s of TCR beta chains, the synovial localization of T cells bearing V beta s with significant CDR4 homology indicates that V beta-specific T-cell activation by superantigen may play a role in RA.

SummaryWe have examined previously the peptide specificity of the T cell response to myelin basic protein (MBP) in patients with multiple sclerosis (MS) and healthy controls, and demonstrated that an epitope spanning amino acids 87-106 was frequently recognized. Because this region is encephalitogenic in some experimental animals, it has been postulated that the response to the epitope may have relevance to MS. In this study, the fine specificity of this response is studied using four well-characterized, monospecific T cell lines from three MS patients and an identical twin of a patient. Each of the lines recognized a peptide with the same core sequence, amino acids 89-99, although the responses were affected to various degrees by truncations at the 000H-or NH2 terminal ends of the 87-106 epitope. Importantly, the epitope was recognized in conjunction with four different HLA-DR molecules. Also, the T cell receptor /3 chain usage was heterogeneous, and each line expressed a different VDJ sequence. The four HLADR molecules restricting the response to this epitope have been shown to be overrepresented in MS populations in various geographic areas, suggesting that the response to this region of the MBP molecule may be relevant to the pathogenesis of MS. These findings may have important implications in designing therapeutic strategies for the disease .Although the cause of multiple sclerosis (MS)' is not 13. known, a T cell-mediated autoimmune process has been postulated. Myelin basic protein (MBP) is a potential target antigen because it induces experimental allergic encephalomyelitis (EAE) in susceptible animals. Encephalitogenic epitopes of MBP differ among susceptible strains and correlate with the MHC class II genotype (1) . The TCRs expressed by encephalitogenic T cells from PL/J and B10YL mice and Lewis rats use the same TCR V(3 chain, V08 .2, and have similarities in their VDJ regions, as reviewed in reference 2. Thus, the pathogenesis of EAE is related to the capacity of T cells with the appropriate TCRs to recognize epitopes of MBP 1 Abbreviations used in this paper. aa, amino acid ; EAE, experimental allergic encephalomyelitis ; HTC, homozygous typing cells; ICAM-1, intracellular adhesion molecule 1; MBP, myelin basic protein; MS, multiple sclerosis ; TCL, T cell line . 19presented in conjunction with class II MHC molecules . These requirements have provided rationales for therapeutic strategies that prevent or treat EAE (3-7).The analysis of the T cell response to MBP in patients with MS and in healthy controls has shown that several regions of the molecule are frequently recognized (8-10). One region, an epitope spanning amino acids (aa) 87-106, was recognized by >50% of T cell lines (TCL) derived from both MS patients and controls (9) . Our findings indicated that several HLADR molecules could serve as restriction elements for MBP or fragments of the molecule . In contrast, other investigators have reported that an epitope spanning as 84-102 is predominantly recognized by TCL from MS patients and large...

The mycobacterial cell wall core consists of an outer lipid layer of mycolic acids connected, via arabinogalactan polysaccharide, to an inner peptidoglycan layer. An a-L-rhamnopyranosyl residue has been shown to be a key component USA linking the mycolated arabinogalactan to the peptidoglycan and, therefore, the biosynthesis of L-rhamnose (Rha) in mycobacteria was investigated as the first step of developing inhibitors of its biosynthesis. Biochemical assays were used to show that dTDP-Rha was synthesized in Mycobacterium smegmatis from a-D-glucose I-phosphate (a-D-Glc-1-P) and dTTP by the same four enzymic steps used by Escherichia coli and other bacteria. PCR primers based on consensus regions of known sequences of the first enzyme in this series, E-D-GIC-I-P thymidylyltransferase (RfbA) were used to amplify rfbA DNA from M. tuberculosis. The entire rfbA gene was then cloned and sequenced. The deduced amino acid sequence revealed a 31 362 Da putative protein product which showed similarity to RfbA proteins of other bacteria (59% identity to that found in E. coli). Sequencing of DNA flanking the rfbA gene did not reveal any of the other rfb genes required for dTDP-Rha biosynthesis. Therefore, the four Rha biosynthetic genes are not clustered in M. tuberculosis. The enzymic activity of the sequenced gene product was confirmed by transformation of E. coli with pBluescript KS(-) containing the rfbA gene from M. tuberculosis. Analysis of enzyme extracts prepared from this transformant revealed an 1 I-fold increase in E-D-GIc-I-P thymidylyltransferase activity.